/*
 * @(#)StatusDetail.java
 *
 * Copyright 2003-2004 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *   2. Redistribution in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed or intended for use in
 * the design, construction, operation or maintenance of any nuclear facility.
 */

package org.wso2.balana.ctx;

import org.wso2.balana.ParsingException;

import java.io.ByteArrayInputStream;

import java.io.IOException;
import java.io.StringWriter;
import java.util.List;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.xml.sax.SAXException;

/**
 * This class represents the StatusDetailType in the context schema. Because
 * status detail is defined as a sequence of xs:any XML type, the data in this
 * class must be generic, and it is up to the application developer to interpret
 * the data appropriately.
 * 
 * @since 1.0
 * @author Seth Proctor
 */
public class StatusDetail {

	// the root node
	private Node detailRoot;

	// the text version, if it's avilable already
	private String detailText = null;

	/**
	 * a List of MissingAttributeDetail
	 */
	private List<MissingAttributeDetail> missingAttributeDetails;

	/**
	 * Constructor that uses a <code>List</code> of
	 * <code>MissingAttributeDetail</code>s to define the status detail. This is
	 * a common form of detail data, and can be used for things like providing
	 * the information included with the missing-attribute status code.
	 * 
	 * @param missingAttributeDetails
	 *            a <code>List</code> of <code>MissingAttributeDetail</code>s
	 * 
	 * @throws IllegalArgumentException
	 *             if there is a problem encoding the
	 *             <code>MissingAttributeDetail</code>s
	 */
	public StatusDetail(List<MissingAttributeDetail> missingAttributeDetails)
			throws IllegalArgumentException {

		this.missingAttributeDetails = missingAttributeDetails;
		try {
			detailText = "<StatusDetail>\n";

			for (MissingAttributeDetail attribute : missingAttributeDetails) {
				detailText += attribute.getEncoded() + "\n";
			}

			detailText += "</StatusDetail>";
			detailRoot = textToNode(detailText);
		} catch (ParsingException pe) {
			// really, this should never happen, since we just made sure that
			// we're working with valid text, but it's possible that encoding
			// the attribute could have caused problems...

			throw new IllegalArgumentException(
					"Invalid MissingAttributeDetail data, caused by "
							+ pe.getMessage());
		}
	}

	/**
	 * Constructor that takes the text-encoded form of the XML to use as the
	 * status data. The encoded text will be wrapped with the
	 * <code>StatusDetail</code> XML tag, and the resulting text must be valid
	 * XML or a <code>ParsingException</code> will be thrown.
	 * 
	 * @param encoded
	 *            a non-null <code>String</code> that encodes the status detail
	 * 
	 * @throws ParsingException
	 *             if the encoded text is invalid XML
	 */
	public StatusDetail(String encoded) throws ParsingException {
		detailText = "<StatusDetail>\n" + encoded + "\n</StatusDetail>";
		detailRoot = textToNode(detailText);
	}

	/**
	 * Private constructor that just sets the root node. This interface is
	 * provided publically through the getInstance method.
	 * 
	 * @param root
	 *            the DOM root of StatusDetail element
	 */
	private StatusDetail(Node root) {
		detailRoot = root;
		try {
			detailText = nodeToText(root);
		} catch (ParsingException e) {
			// just ignore as this is not a must to convert this to text
		}
	}

	/**
	 * Private helper routine that converts text into a node
	 * 
	 * @param encoded
	 * @return
	 * @throws ParsingException
	 */
	private Node textToNode(String encoded) throws ParsingException {
		try {
			String text = "<?xml version=\"1.0\"?>\n";
			byte[] bytes = (text + encoded).getBytes();

			DocumentBuilderFactory factory = DocumentBuilderFactory
					.newInstance();
			DocumentBuilder db = factory.newDocumentBuilder();
			Document doc = db.parse(new ByteArrayInputStream(bytes));

			return doc.getDocumentElement();
		} catch (ParserConfigurationException e) {
			throw new ParsingException("invalid XML for status detail");
		} catch (SAXException e) {
			throw new ParsingException("invalid XML for status detail");
		} catch (IOException e) {
			throw new ParsingException("invalid XML for status detail");
		}
	}

	/**
	 * Private helper routine that converts text into a node
	 * 
	 * @param node
	 * @return
	 * @throws ParsingException
	 */
	private String nodeToText(Node node) throws ParsingException {

		StringWriter sw = new StringWriter();
		try {
			Transformer transformer = TransformerFactory.newInstance()
					.newTransformer();
			transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION,
					"yes");
			transformer.setOutputProperty(OutputKeys.INDENT, "yes");
			transformer.transform(new DOMSource(node), new StreamResult(sw));
		} catch (TransformerException te) {
			throw new ParsingException("invalid XML for status detail");
		}
		return sw.toString();
	}

	/**
	 * Creates an instance of a <code>StatusDetail</code> object based on the
	 * given DOM root node. The node must be a valid StatusDetailType root, or
	 * else a <code>ParsingException</code> is thrown.
	 * 
	 * @param root
	 *            the DOM root of the StatusDetailType XML type
	 * 
	 * @return a new <code>StatusDetail</code> object
	 * 
	 * @throws ParsingException
	 *             if the root node is invalid
	 */
	public static StatusDetail getInstance(Node root) throws ParsingException {
		// check that it's really a StatusDetailType root
		if (!root.getNodeName().equals("StatusDetail")) {
			throw new ParsingException("not a StatusDetail node");
		}
		return new StatusDetail(root);
	}

	/**
	 * Returns the StatusDetailType DOM root node. This may contain within it
	 * any type of valid XML data, and it is up to the application writer to
	 * handle the data accordingly. One common use of status data is to include
	 * <code>Attribute</code>s, which can be created from their root DOM nodes
	 * using their <code>getInstance</code> method.
	 * 
	 * @return the DOM root for the StatusDetailType XML type
	 */
	public Node getDetail() {
		return detailRoot;
	}

	/**
	 * Gets List of <code>MissingAttributeDetail</code> elements
	 * 
	 * @return a <code>List</code> of <code>MissingAttributeDetail</code>
	 */
	public List<MissingAttributeDetail> getMissingAttributeDetails() {
		return missingAttributeDetails;
	}

	/**
	 * Returns the text-encoded version of this data, if possible. If the
	 * <code>String</code> form constructor was used, this will just be the
	 * original text wrapped with the StatusData tag. If the <code>List</code>
	 * form constructor was used, it will be the encoded attribute data. If this
	 * was created using the <code>getInstance</code> method, then
	 * <code>getEncoded</code> will throw an exception.
	 * 
	 * @return the encoded form of this data
	 * 
	 * @throws IllegalStateException
	 *             if this object was created using the <code>getInstance</code>
	 *             method
	 */
	public String getEncoded() throws IllegalStateException {
		if (detailText == null) {
			throw new IllegalStateException("no encoded form available");
		}
		return detailText;
	}

}
